IN U.S. Atlantic salt marshes, the purple marsh crab, Sesarma reticulatum, creates fronts as it consumes the smooth cordgrass, Spartina alterniflora. Sesarma fronts form at the heads of tidal creeks and move directionally inland, creating distinct zonation between the tall-form Spartina low marsh and the short-form Spartina high marsh, separated by a denuded bang of mudflat. Sesarma's direct consumption of Spartina and its burrowing activities, which resuspend previously consolidated sediments and organic matter, pose a threat to the resilience of salt marshes and their carbon pools. Using a combination of field-derived and remote sensing data, we are examining the effects of Sesarma fronts on saltmarsh carbon stocks and quantifying carbon fluxes as the front propagates through marshes in Georgia, South Carolina, and Virginia. (Wittyngham, Johnson, Chen, & Kirwan, in prep)